Question 1060952
.
A scientist has two solutions, which she has labeled Solution A and Solution B. Each contains salt. She knows that Solution A is 
65% salt and Solution B is 80% salt. She wants to obtain 30 ounces of a mixture that is 70% salt. 
How many ounces of each solution should she use?
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<pre>
I am not a chemist, but know (from the school, from the literature, from "the air") that at normal conditions 
the maximal possible concentration of salt (common table salt NaCl) in water is about 37%.

You can read more about it from the Internet.

But here, I understand, only the Math problem is considered without questioning on feasibility.

OK. The solution is as follows:

Let A be the volume of the 65% solution to be mixed, in ounces. 
Then the volume of the 80% solution to be mixed is (30-A) ounces.

Then you have this "salt concentration" balance equation

0.65*A + (30-A)*0.8 = 0.7*30.

Simplify and solve for A:

0.65A + 24 - 0.8A = 21,

0.65A - 0.8A = 21 - 24,

-0.15A = -3,

A = {{{(-3)/(-0.15)}}} = 20.

<U>Answer</U>.  20 ounces of the 65% solution must be mixed with 30-20 = 10 ounces ot the 80% solution.
</pre>

There is entire bunch of lessons covering various types of mixture problems

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Mixture-problems.lesson>Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/More-Mixture-problems.lesson>More Mixture problems</A>

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=http://www.algebra.com/algebra/homework/word/mixtures/Solving-typical-mixture-problems.lesson>Solving typical word problems on mixtures for solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-antifreeze-solutions.lesson>Word problems on mixtures for antifreeze solutions</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Word-problems-on-mixtures-for-alloys.lesson>Word problems on mixtures for alloys</A> 

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/word/mixtures/Typical-word-problems-on-mixtures-from-the-archive.lesson>Typical word problems on mixtures from the archive</A>

in this site.


Read them and become an expert in solution the mixture word problems.


Also, you have this free of charge online textbook in ALGEBRA-I in this site

&nbsp;&nbsp;&nbsp;&nbsp;- <A HREF=https://www.algebra.com/algebra/homework/quadratic/lessons/ALGEBRA-I-YOUR-ONLINE-TEXTBOOK.lesson>ALGEBRA-I - YOUR ONLINE TEXTBOOK</A>.


The referred lessons are the part of this textbook in the section "<U>Word problems</U>" under the topic "<U>Mixture problems</U>".